Check out the housewares department at your local department store, I got one from the Bay for around $10 or $15 bucks, but I would recommend not buying one with a wood pestle, I got rid of that one and I have a marble one that I bought at the PNE for $20 bucks.
Pendery's catalogue has a wonderful selection of all different kinds of mortars and pestles including the lava molcajete which retails for $14.95. There are marble and wood also. They have a website and you can probably find these items on it: http://www.penderys.com. Happy Hunting.